800G DSP ASIC Design Using Probabilistic Shaping and Digital Sub-Carrier Multiplexing

TLDR

ASIC design underpins modern ultra‑high‑speed transponders that rely on advanced DSP algorithms. The paper explores why probabilistic shaping and digital sub‑carrier multiplexing should be combined in digital coherent optical transmission systems. It outlines the key building blocks of high‑speed DSP‑based transponders operating at up to 800 Gb/s per wave. The authors demonstrate that these techniques improve system‑level performance and report the first >1000 km long‑haul experiment with a real‑time 7 nm DSP ASIC and DCO achieving 1.6 Tb/s using two 800 Gb/s waves.

Abstract

The design of application-specific integrated circuits (ASIC) is at the core of modern ultra-high-speed transponders employing advanced digital signal processing (DSP) algorithms. This manuscript discusses the motivations for jointly utilizing transmission techniques such as probabilistic shaping and digital sub-carrier multiplexing in digital coherent optical transmissions systems. First, we describe the key-building blocks of modern high-speed DSP-based transponders working at up to 800G per wave. Second, we show the benefits of these transmission methods in terms of system level performance. Finally, we report, to the best of our knowledge, the first long-haul experimental transmission – e.g., over 1000 km – with a real-time 7 nm DSP ASIC and digital coherent optics (DCO) capable of data rates up to 1.6 Tb/s using two waves (2 × 800G).